Carbon nanotubes (CNTs) include carbon-based fullerene structures that include single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs).
Dye-sensitized solar cells (DSSCs) are solar cells that are potentially more cost-effective than conventional semiconductor solar cells. In an illustrative example, a DSSC can receive sunlight through a transparent conductive anode, such as made of fluorine-doped tin oxide deposited on the back of a glass plate. In this example, on the back of the conductive anode plate is a thin layer of titanium dioxide, which forms a porous structure. A dye is covalently bonded to the titanium dioxide particles, in this example. An iodide/triiodide electrolyte is interposed between the anode and a catalytic conductive (e.g., platinum) cathode, in this example. In operation of this example, sunlight received through the conductive anode excites the dye to inject an electron into the conduction band of the titanium dioxide. In this example, the electron injected by the dye is replaced by an electron from the electrolyte, which oxidizes iodide into triiodide. The triiodide diffuses to the cathode to receive an electron via current flow through the external load circuit of the DSSC, in this example. The DSSC cathode, therefore, injects charge into the electrolyte and catalyzes the reduction of triiodide, in this example. As mentioned above, a DSSC is potentially somewhat more cost-effective at converting sunlight into electricity than a conventional semiconductor solar cell.